Acrophonic numeral signs use the first letter of certain numbers and currency values to stand for the whole: pi stands for πέντε, delta for δέκα, heta for ἑκατόν, and so on. Individual signs may be combined within a single character to represent compound values: the value 50, for example, in the acrophonic system is represented by a delta (δέκα: 10) written within a pi (πέντε: 5), to indicate 5 x 10.

The Greek acrophonic numerals are now in Unicode, and EpiDoc recommends that these characters now be used and simply tagged as any other numeral or currency measure.